Satellite systems for worldwide navigation (Global Navigation Satellite System GNSS, satellite navigation system for short) are used for position determination and navigation on the ground and in the air. In order for a receiver to determine a given position, navigation messages are transmitted in the GNSS via the satellite signals. These navigation messages contain, among other things, data about the orbit of the satellite that is sending the satellite signal containing the messages. The messages are transmitted at certain time intervals in order to transmit the most current orbit data possible to receivers so as to attain precise position determination. In the European GNSS Galileo (below also referred to as the Galileo system or Galileo for short), which is being set up at this time, the current specification makes use of the following parameters for the orbit description in a navigation system:                M0: mean anomaly at reference time        Δn: mean motion difference from computed value        e: eccentricity        A1/2: square root of the semi major axis        OMEGA0: longitude of ascending node of orbital plane at weekly epoch        i0: orbit inclination angle at reference time        OMEGA: argument of perigee        OMEGADOT: rate of change of longitude of the ascending node at the weekly epoch        IDOT: rate of change of inclination angle        cuc: amplitude of the cosine harmonic correction term to the argument of latitude        cus: amplitude of the sine harmonic correction term to the argument of latitude        crc: amplitude of the cosine harmonic correction term to the argument of latitude        crs: amplitude of the sine harmonic correction term to the orbit radius        cic: amplitude of the cosine harmonic correction term to the angle of inclination        cis: amplitude of the sine harmonic correction term to the angle of inclination        t0e: ephemeris reference time        
However, the navigation message for Galileo only provides for very few bits for future expansions, which of course limits any later expansion of the Galileo system by new services and additional information.